In the field of arthroscopic surgery various suturing instruments have been used for stitching internal tissues of the body. An object of such surgical procedures is to minimize the invasiveness of the surgical instrument in performing a given surgical procedure, whether diagnostic or restorative. This object is achieved by making a small incision in the overlying tissue layers to provide the surgeon access the site of interest. The surgeon may then insert the surgical instrument through the small incision and perform the desired procedure.
In many procedures, the surgeon will need to insert a stitch to join body tissues at the site of interest. A suturing instrument such as that disclosed by Caspari, et al., in U.S. Pat. No. 4,957,498, will typically be used for joining tissues internal a patient's body. Such suturing instruments provide a hollow tissue penetrating needle through which the surgeon feeds a length of suture material. The suture material is fed by manipulation of a thumbwheel. After insertion of the suture material through the tissues the free end of the suture material is withdrawn with the instrument through the incision to a point external the patient's body. The surgeon then knots the suture material and manipulates the suture material to urge the knot back through the incision to a point adjacent to the joined tissues.
In practicing the invention disclosed by Caspari, the inventor has noticed the difficulty experienced by surgeons in manipulating the suture feed mechanism while maintaining the jaws of the instrument in the closed, tissue penetrating position. Moreover, the instrument disclosed by Caspari et al, requires the surgeon to coax the free end of the suture material to a point external the patient's body while at the same time feeding additional suture material by manipulation of the thumb wheel.
Should the surgeon loose the free end of the suture material during retraction of the instrument, additional intrusion into the body cavity is necessary to retrieve the suture free end for tying the desired stitch. In addition, should the free end of the suture be inadvertently pulled free of the tissue penetration points, additional tissue insult may be necessary to reinsert the suture material through the tissues. Accordingly, there is a need for a suturing instrument that provides an improved suture material feed and retraction mechanism.